The chemical state change on the cresol-novolak photoresist surfaces was investigated using Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and some basic information of the chemical reactions caused by UV irradiation were obtained. The photoresist sample used in this study was a mixture of the base polymer of cresol-novolak resin and an additive which has naphtoquinonediazide as the photosensitive materials. This photoresist was coated on a Si wafer and then exposed to a 254 nm UV light over varied periods of time. It was clearly observed that the intensity of the peaks resulting from the scissioning of the chemical bonds and oxidation of the polymer backbone increased with the increase of exposure time. We also investigated the same samples using XPS and FT-IR. It was demonstrated that TOF-SIMS provides more sensitive information on the slight change of chemical state due to chemical bond scissioning and oxidation than XPS or FT-IR and that this technique is quite useful for the surface characterization of this kind of photoresist materials.
